The present invention generally relates to an implement having an improved hitch and to an improved hitch for an implement. More particularly, the invention relates to a hitch apparatus for connecting an agricultural or industrial implement or the like to a tractor or other pulling vehicle, as well as to such implements having the hitch apparatus. The hitch apparatus includes a hitch component pivotally secured to a clevis component along a generally horizontal axis. The hitch component is secured, preferably in a rotatable manner, to the tongue portion of the implement. The clevis component is arranged to receive the drawbar of the pulling vehicle and is secured thereto by a hitch pin or similar connecting member. The hitch bears down on the clevis at a location which is forward of the connecting member. With this arrangement, the front portion of the hitch bears the weight of the implement. In addition, the implement is free to move upwardly and downwardly in view of the rotational mounting between the hitch and clevis. Although the invention is not so limited, the hitch apparatus is particularly useful as a component of a rotary cutter type of implement.
In a typical implement hitch arrangement, a clevis is provided which generally brackets the drawbar of a tractor or other pulling vehicle, and a hitch pin passes through one lip or wing of the clevis, then through the tractor drawbar, and finally through the other lip or wing of the clevis. In such a standard hitch arrangement, the implement has a limited range of vertical movement vis-a-vis the pulling vehicle which will allow the implement to traverse certain terrain variations by virtue of lever-type movement that is allowed by the vertical spacing between the lips of the clevis and the drawbar. The latter movement with a standard hitch arrangement allows some limited vertical motion when the vehicle pulls the implement over the crest of a knoll or a hill or through a gully or ravine. At these times, the contact surface area, and thus the load-transmitting area, is substantially reduced when compared to the load transfer area that is present when the clevis lip is generally parallel to the tractor drawbar, which is rarely the case when the tractor and implement move over normal terrain being traversed by the tractor and implement.
With a standard hitch as discussed hereinabove, the contact area between the hitch clevis and the tractor drawbar is relatively small. In addition, this small contact area is subjected to relatively high stresses when the clevis constantly engages, disengages and engages again a portion of either the top or bottom surface of the tractor drawbar as the implement is pulled through a field or the like. In this standard hitch arrangement, the clevis does not remain parallel to the drawbar, but moves through various acute angles with respect to the drawbar, depending upon the particular attitude of the implement. This decreases contact surface area as generally discussed above, which increases wear and also increases the likelihood of damage to the drawbar and/or the clevis or other hitch components.
Also, with a standard hitch, the range of movement in the up and down directions is limited by the "play" or spacing between the clevis lips and the drawbar. A tight fit in this regard substantially narrows the range of vertical movement. While increased spacing between the lips of the clevis could provide additional vertical movement, this is often at the expense of hitch control and long life of the components at the hitching location.
With standard hitch arrangements, the weight of the implement is typically transmitted to the drawbar in the vicinity of the hitch pin. The hitch pin hole is typically near the free end of the drawbar and thus is relatively far from the location at which the drawbar is secured to the pulling vehicle. Consequently, the transfer weight of the implement is imparted to the drawbar at a location spaced relatively far away from the drawbar support location, and relatively large stresses can thus be placed on the drawbar, as a result of which the load carrying capacity of the drawbar is less than could be possible if the weight of the implement were to be positioned at a location closer to the drawbar support location.
Previous approaches have attempted to improve upon typical standard hitching arrangements. For example, U.S. Pat. No. 2,867,452 shows a clevis which pivots on a cross-pin inserted through arms of a weldment. This weldment is journalled into a block of a trailer unit. This permits rotation about the entirety of the hitch assembly. A bolt retains the hitch assembly to the drawbar of a tractor. This type of a hitch assembly allows for a "universal" type of movement.
U.S. Pat. No. 4,200,306 describes a tractor drawbar inserted into a clevis provided with a tube arranged for receiving a pivot bolt. This pivot bolt passes through trunnions which are welded to a plate. This plate has a collar welded to it, which collar is journalled on a tube shaft extending through a hole to provide it in a base. Such base is mountable onto an agricultural implement so as to permit rotation of the weldment. This patent requires a specific bearing assembly for achieving its objectives. The structure of either of these patents does not remove various deficiencies found in typical standard hitch arrangements as generally discussed above.
Also, approaches such as those shown in U.S. Pat. No. 4,711,461 are intended to provide trailer hitches to achieve coupling about three independent axes. In the particular arrangement of this patent, two separate U-shaped yoke members are required. Also required are structures such as a bolt extending between opposite ends of two cylindrical members and through the center of a hollow, cylindrical sleeve to retain cylindrical member surfaces in abutment with each other. While the yoke member is shown for mounting on a trailer by means of a rotatable joint, it has a coupling web member which does not swing vertically, although the hinge pin does permit such movement. Also, this arrangement is not one wherein the hitch assembly readily connects to a standard horizontally oriented drawbar of a tractor or the like.
The present invention avoids the various disadvantages of standard hitch arrangements as generally discussed herein while also improving upon various other approaches such as those of the patents discussed herein. This is achieved while providing a hitch arrangement wherein the clevis remains parallel to the drawbar regardless of the attitude of the implement as it is being pulled through the field or other ground area being worked by the implement.
In summary, the implement hitch in accordance with the present invention attaches a tow-behind implement to a pulling vehicle such as a tractor. The invention also encompasses an implement having such a hitch. The hitch assembly is secured to the tongue or the like of the tow-behind implement. The implement hitch further includes an offset hitch component that extends generally forwardly to provide operative connection to the clevis assembly for operatively securing the hitching apparatus to the drawbar or the like of the pulling vehicle. Holes are provided for passing a hitch pin through the clevis and drawbar in order to thereby provide the attachment between the implement hitch and the towing vehicle. The weight of the implement is transmitted to the drawbar at a location forward of the hitch pin securement location. The offset hitch member is pivotally secured to the clevis assembly at this forward location. This pivotal securement includes a pivot mount location which is generally horizontal and which encompasses a forwardly extending clevis surface which is in front of the pivot pin location.
It is a general object of the present invention to provide an improved implement hitch as well as implements which are improved by incorporating same.
Another object of the present invention is to provide an improved implement hitch and implement by which farm or industrial implements are attached to tractor drawbars by a positive but flexible connection between the implement and the tractor.
Another object of the present invention is to provide an improved implement hitch and implement wherein the clevis is substantially parallel to the drawbar during operation, regardless of the attitude of the implement.
Another object of the present invention is to provide an improved implement hitch and implement having an increased contact surface area between the drawbar and the clevis while the implement is being pulled and used, thereby reducing wear and the possibility of drawbar damage.
Another object of the present invention is to provide an improved implement and implement hitch structured such that the weight of the implement is transferred to the drawbar at a location ahead of the hitch pin, thereby reducing stress on the drawbar and increasing the load carrying capacity of the drawbar.
Another object of the present invention is to provide an implement and implement hitch exhibiting rotational attributes that are improved over standard hitch arrangements, including increased angular movement of the hitch to facilitate crossing of rougher terrain without damage to the drawbar or hitch components.
Another object of the present invention is to provide an improved implement and implement hitch having a clevis with a relatively short lower lip which hangs at a favorable angle from the hitch prior to connection to the tractor in order to allow the tractor operator to back the tractor drawbar into the hitch in a relatively easy manner despite the fact that the clevis is pivotable on, rather than rigidly mounted to the implement hitch.
These and other objects, features and advantages of the present invention will be clearly understood through a consideration of the following detailed description.